The emphasis of our research is on the genetic determinants and modifying environmental factors in the development of hypertension. Our unique tool for studying experimental hypertension is a rat colony consisting of two selected lines with opposite, genetically determined predispositions to hypertension inducible by any one of a number of the commonly used procedures. Our major objectives with respect to these rats are: 1) To produce inbred strains of the Dahl hypertension-resistant and hypertension-sensitive selected lines. This will allow better control over the genetic variable involved in hypertension and will also eventually enable other institutions to maintain their own colonies of these animals; and 2) to continue to characterize the specific role of the kidney in the pathogenesis of experimental hypertension.